Preparation of dinitrotoluene and trinitrotoluene with boron trifluoride and nitric acid



United States Patent 3,293,310 PREPARATION (HF DTNHTROTOLUENE AND TRE- NITROTGLUENE WITH BEGRON TREFLUURTDE AND NITRIC ACT!) Jean P. Picard, Morristown, Daniel R. Satriana, Verona, and Louis Silberman, Dover, N..l., assignors to the United States of America as represented by the Secretary of the Army N0 Drawing. Filed Feb. 8, 1966, Ser. No. 526,335 8 Claims. (Cl. 260-645) IINOa HzSOq (30 C.)

The quantity of H 80 required for the manufacture of TNT by the above process is large. TNT is a high explosive, relatively insensitive to shock and fulfills vital military as well as industrial needs. To counter-act the possibility of shortages of this acid in times of emergency, various unsuccessful attempts have been made to eliminate the necessity of using H 80 in the manufacture of TNT.

It is therefore a broad object of this invention to provide methods of manufacturing TNT wherein the use of H 50 is not required.

Another object of this invention is to provide methods for the manufacture of TNT wherein a l-step nitration process only is required.

Still another object of this invention is to provide meth- Ods to efliciently convert toluene to DNT by spent acid formed in our l-step nitration process above mentioned.

Other objects and advantages of the invention will be obvious or appear hereinafter in the following detailed description.

Briefly, we have discovered that toluene and a mixed acid consisting of B1 and HNO can be reacted to yield 86.4% of TNT having a purity of about 92.5%.

More specifically, we have discovered that when HNO having a concentration of 98.6%, and 30 to 60% BF is mixed therewith to form a mixed acid, reacted with toluene for 30 to 240 minutes and refluxed, that high yields and purities of TNT can readily be produced.

The toluene to nitric acid molar ratio must be in excess of 1 to 3, although molar ratios approximating 1 to are preferred. A minimum reflux time of about 1 hour is required in nitration wherein the BE ranges from between about 30 to 60 weight percent. Excellent yield and purity of TNT may be obtained when the mixed acid concentration is 40 weight percent B1 and 60 weight percent HNO (98.6%) and refluxed for about 2 hours. The difference in density between the TNT and spent acid permits a clean separation of the TNT product from the reaction medium.

The reflux temperature will normally be about 90-95 C. and the reaction temperature during the addition of toluene will normally be maintained between about 3050 C.

The spent acid formed in our l-step nitration process can effectively be used to nitrate toluene to produce DNT in yields approaching 76%. The DNT thus formed can be further nitrated with fresh mix-ed acid, preferably BF /HNO (98.6%) in weight ratio of 40/60 to realize an 83% yield of TNT having a purity of about The time of reflux for converting DNT with out spent acid is about 5 minutes whereas reflux time for converting DNT to TNT is approximately 2 hours.

We have found that a product having slightly better yields and purities are obtained with mixed acids containing by weight percent 40BF /6OHNO (98.6%) than 2.0BF /80HNO (98.6%) and 60BF /40HNO (98.6%). The overall recovery of spent acid ranged from about 50 to 72 weight percent in nitrations that contained 5P concentrations of about 40%.

Although it is not intended that the invention be limited thereto, there is set forth hereinbelow for purposes of illustration, examples of values which may suitably be employed in practicing our invention, all percentages being weight percentages:

Example 1 18 grams (0.195 moie) of toluene were added to 200 grams of mixed acid consisting of 60% B1 and 40% HNO (98.6%). During the addition, the mixture was stirred vigorously and temperature maintained between 3050 C. by means of a cooling bath. After addition of toluene was completed, the reaction was refluxed (-95 C.) for one hour, cooled to about 70 C., and transferred to a separatory funnel. The two liquid phases were separated.

The upper layer, consisting mainly of trinitrotoluene, was poured into ice water. The product was filtered, washed free of acid and dried. The lower layer (162 g.), consisting of spent acid and some residual product, was also poured into an ice-water mixture. The solid, after filtering, washing and drying, was added to the main portion. The total Weight of crude trinitrotoluene was 35.3 g. (79.3% of theoretical) having a purity of 65.6%.

Example II This example is identical with Example I except reflux time was increased to 2 hours. The yield of crude trinitrotoluene was 36.4 g. (81.7 of theoretical) having a purity of 76.2%. The weight of spent acid was 164 grams or 82.6% recovery.

Exam ple III This example is identical with Example I except reflux time was increased to 3 hours. The crude yield of trinitrotoluene was 36.4 g. (81.7% of theoretical) having a purity of 84.9%. The weight of spent acid was g. of 80.1% recovery.

Example IV 18 grams (0.195 mole) of toluene were added to 200 grams of mixed acid consisting of 50% B1 and 50% I'INOg (98.6%). The experimental procedure was identical to that described in Example I. The crude yield of trinitrotoluene (79.5% purity) was 37.1 grams or 83.4% of theoretical. The weight of spent acid was 159 grams or 79.6% recovery.

Example V This example is identical with Example IV except reflux time was increased to 2 hours. The crude yield of trinitrotoluene (89.1% purity) was 36.6 grams or 82.1% of theoretical. The weight of spent acid was 160 grams or 79.8% recovery.

Example Vl This example is identical with Example IV except reflux time was increased to 3 hours. The yield of crude trinitrotoluene (91.4% purity) was 36.8 grams or 82.7% of theoretical. The weight of spent acid was 158 grains (79.0% recovery).

Example VII 18 grams (0.195 mole) of toluene were added to 200 grams of mixed acid consisting of 40% BF and 60% HNO (98.6%). The experimental procedure was similar to that described in Example I. The time of reflux for the reaction was one hour. 37.5 grams (84.2% theoretical) of crude trinitrotoluene (79.2% purity) was obtained. The weight of spent acid was 144 grams or 71.9% recovery.

Example VIII This example is identical with Example VII except reflux time was increased to 2 hours. 38.4% (of theoretical) of crude trinitrotoluene (92.5% purity) was obtained. The weight of spent acid was 135 grams or 67.6% recovery.

Example IX This example is identical with Example VII except reflux was increased to 3 hours. The yield of crude trinitrotoluene (88.4% purity) was 38.3 grams or 86.0% of theoretic-a1. The weight of recovered spent acid was 144 g. (71.9%).

Example X 18 grams (0.195 mole) of toluene were added to 200 grams of mixed acid consisting of 30% BF and 70% HNO (98.6%). The experimental procedure was the same as that described in Example I. 36.8 grams (82.7% of theoretical) of crude trinitrotoluene (70.2% purity) was obtained. No separation of liquid phases had occurred between the product and the spent acid using the above mixed acid concentration.

Example XI This example is identical with Example X except reflux time was increased to 2 hours. The yield of crude trinitrotoluene (85.5% purity) was 38.3 g. (86.0% of theoretical) and no spent acid was recoverable by liquid phase separation.

Example XII This example is identical with Example X except reflux time was increased to 3 hours. The yield of crude trinitrotoluene (86.6% purity) was 37.8 g. (85.0% of theoretical) and no spent acid was recoverable by liquid phase separation.

Example III A mixture of 200 grams of mixed acid consisting of 60% BF and 40% HNO (98.6%), and 54 grams (0.297 mole) of 2,4-dinitrotoluene (DNT) was refluxed (90 C-95 C.) under constant stirring for a period of two hours. The reaction mixture was cooled to about 70 C, then transferred to a separatory funnel to permit separation of the liquid phases. The top layer, consisting mainly of trinitrololuene (TNT), was poured into ice water. The product was filtered, washed free of acid and dried. The yield of crude TNT (62.5% purity) was 54.1 grams (80.2% of theoretical). 18 grams (0.195 mole) of toluene was added under vigorous stirring to the recovered spent acid (171 grams) while the temperature of the reaction was maintained between 30 C. to 50 C. After the addition of toluene was completed, the mixture was heated .81 reflux (90 C.95 C.) for five minutes, cooled to about 70 C., and then poured into ice water. The solid was filtered, washed free of acid with water, and dried. The weight of crude of crude dinitrotoluene was 21.6 g. (60.7% of theoretical). The lower layer, consisting of spent acid, was 143 grams.

Example XIV This example is identical with Example XIII except the IITIIXd acid concentration was changed to BF 50% HNO (98.6% The yield of crude trinitrotoluene (78.0% purity) was 56.3 grams (83.5% of theoretical). 157 grams of recovered spent acid was used to convert 18 grams of toluene to 25.2 grams (70.8% theoretical) 133 g. of spent acid was recovered.

Example XV of dinitrotoluene.

This example is identical with Example XIII except the mixed acid concentration was changed to 40% BF HNO (98.6% The yield of crude trinitrotoluene (79.5% purity) was 56.1 grams (83.2% of theoretical). 126 grams of recovered spent acid was used to convert 18 grams of toluene to 26.9 grams (75.8% of theoretical) of dinitrotoluene. 99 grams of spent acid was recovered.

Example XVI Example XVII This example is identical with Example XIV except the I-INO concentration was changed to 95.7%. The yield of crude trinitrotol-uene (72.0%) was 54.9 grams (81.5 of theoretical). 157.5 grams of recovered spent acid was used to convert 18 grams of toluene to 23.6 grams (66.5% of theoretical) of dinitrotoluene. 133 grams of spent acid was recovered.

We claim:

1. A process for preparing an explosive selected from the group consisting of 2,4,6-trinitrotoluene and 2,4-dinitrotoluene comprising the steps of reacting toluene with a mixture of boron trifluoride and nitric acid, and refluxing the reacted mixture. 2. The process of claim 1 wherein said explosive consists of 2,4,6-trinitrotoluene and said reacting step comprises reacting toluene with a mixture of about 30 to 60 weight percent B1 and the remainder HNO having a concentration of about 98.6%, the molar ratio of said toluene to said HNO ranging from about 1 to 3 to 1 to 10. 3. The process of claim 1 wherein said explosive consists of 2,4,6-trinitrotoluene and said reacting step comprises vigorously stirring at a temperature of about 30 to 50 C. about 18 grams of toluene with about 200 grams of a mixture of 40 to 60 weight percent BF and 60 to 40 weight percent HNO having a conoentration of about 98.6%, and wherein the refluxed mixture is cooled to about C., additionally characterized by transferring the cooled refluxed mixture to a separatory funnel and permitting an upper liquid phase and a lower liquid phase to form,

pouring said upper liquid phase comprising mainly 2,4,6-trinitrotoluene into ice water to form a product,

filtering, washing and drying said product to obtain said 2,4,6-trinitrotoluene.

4. The process of claim 3 further characterized by the steps of pouring said lower liquid phase comprising spent acid and residual 2,4,6-trinitrotoluene into ice water to form a second product,

filtering, washing and drying said second product to obtain additional 2,4,6-trinitrotoluene.

5. The process of claim 1 wherein said explosive consists of 2,4,6-trinit rotoluene and said reacting step cornprises vigorously stirring at a temperature of about 30 to 50 C. about 18 grams of toluene in about 200 grams of a mixture of 30 Weight percent BF and 70 weight percent HNO having a concentration of about 98.6%, and wherein the refluxed mixture is cooled to about 70 C., additionally characterized by pouring the cooled refluxed mixture comprising mainly 2,4,6-trinitrotoluene into ice water to form a product, filtering, washing and drying said product to obtain said 2,4,6-trinitrotoluene.

6. The process of claim 1 wherein said explosive consis-ts of 2,4-dinitrotoluene and said reacting step comprises vigorously stirring at a temperature of about 30 to 50 C. about 54 grams of 2,4-dinitrotoluene in about 200 grams of a mixture of 30 to 60 weight percent BF and 70 to 40 weight percent HNO having a concentration of about 98.6%,

and said refluxing period is about 60 to 180 minutes,

additionally including the steps of cooling the refluxed mixture to about 70 C.,

transferring the cooled refluxed mixture to a separatory tunnel to form an upper liquid phase and a lower liquid phase comprising mainly spent acid, vigorously stirring about 18 grams of toluene added to said lower liquid phase While maintaining the temperature at about 30 to C. to form a second mixture,

refluxing said second mixture at about 90 to 95 C.

for about 5 minutes,

cooling said refluxed second mixture to about C.,

transferring said cooled refluxed second mixture into a separatory funnel to form a second upper liquid phase and a second lower liquid phase, said second upper liquid phase comprising mainly 2,4-dinitrotoluene,

pouring said second upper liquid phase into ice water to form a product,

filtering, washing and drying said product to obtain said 2,4-dinitrotoluene.

7. The process as described in claim 6 further characterized by said nitric acid having a concentration of about 95.7%.

8. The process as described in claim 1 wherein the reacted tmixture is refluxed at a temperature of about C. for a period ranging between about 30 to 240 minutes.

References Cited by the Examiner Bach-man et aL: J. Am. Chem. Soc., vol. 80, pp. 2987 to 2991 (1958).

Heertjes et al.: Chemisch Weekblad, vol. 54, pp. 314 to 318 (1958).

CARL D. QUARFORTH, Primary Examiner.

L. A. SEBASTIAN, Assistant Examiner. 

1. A PROCESS FOR PREPARING AN EXPLOSIVE SELECTED FROM THE GROUP CONSISTING OF 2,4,6-TRINITROTOLUENE AND 2,4-DINITROTOLUENE COMPRISING THE STEPS OF RECACTING TOLUENE WITH A MIXTURE OF BORON TRIFLUORIDE AND NITRIC ACID, AND REFLUXING THE REACTED MIXTURE. 